3.1.1 File format grammar

The meta syntax in this section uses the following conventions:
‘|’ (U+7C) separates alternatives;
‘{’ (U+7B) and ‘}’ (U+7D) enclose optional phrases;
‘{’ and ‘}*’ (trailing U+2A) enclose phrases that can be
repeated zero or more times;
‘{’ and ‘}+’ (trailing U+2B) enclose phrases that must
appear at least once and can be repeated;
terminal symbols are in ‘""’ (two U+22).